Gas Separation Control in Spatial Atomic Layer Deposition

ABSTRACT

Apparatus and methods for spatial atomic layer deposition including at least one first exhaust system and at least one second exhaust system. Each exhaust system including a throttle valve and a pressure gauge to control the pressure in the processing region associated with the individual exhaust system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/744,560, filed Jan. 16, 2020, which is a continuation of U.S. patentapplication Ser. No. 14/840,485, filed Aug. 31, 2015, now U.S. Pat. No.10,570,511, issued Feb. 25, 2020, which claims priority to U.S.Provisional Application No. 62/048,768, filed Sep. 10, 2014, the entiredisclosures of which are hereby incorporated by reference herein.

FIELD

Embodiments of the disclosure generally relate to an apparatus forprocessing substrates. More particularly, embodiments of the disclosurerelate to apparatus and methods for controlling the gas separation in aspatial atomic layer deposition chamber.

BACKGROUND

Semiconductor device formation is commonly conducted in substrateprocessing systems or platforms containing multiple chambers, which mayalso be referred to as cluster tools. In some instances, the purpose ofa multi-chamber processing platform or cluster tool is to perform two ormore processes on a substrate sequentially in a controlled environment.In other instances, however, a multiple chamber processing platform mayonly perform a single processing step on substrates. The additionalchambers can be employed to maximize the rate at which substrates areprocessed. In the latter case, the process performed on substrates istypically a batch process, wherein a relatively large number ofsubstrates, e.g. 25 or 50, are processed in a given chambersimultaneously. Batch processing is especially beneficial for processesthat are too time-consuming to be performed on individual substrates inan economically viable manner, such as for atomic layer deposition (ALD)processes and some chemical vapor deposition (CVD) processes.

The concept of spatial ALD is based on a clear separation of differentgas phase reactive chemicals. Mixing of the chemicals is prevented toavoid gas phase reactions. The general design of a spatial ALD chambermay include a small gap between susceptor (or wafer surface) and gasinjector. This gap can be in the range of about 0.5 mm to about 2.5 mm.Vacuum pumping channels are positioned around each chemical showerhead.Inert gas purge channels are between the chemical showerheads tominimize gas phase mixing. In spite of these intrinsic design features,the gas flow and pumping level are managed to avoid gas phase mixing ofchemicals from different channels. There is an ongoing need in the artfor apparatus and methods for minimizing gas phase mixing.

SUMMARY

One or more embodiments of the disclosure are directed to depositionsystems including a processing chamber. The processing chamber has wallsdefining a chamber volume. The processing chamber includes a susceptorassembly and a gas distribution assembly and has at least one firstprocessing region between the gas distribution assembly and thesusceptor assembly and at least one second processing region between thegas distribution assembly and the susceptor assembly. Each of the atleast one first processing region and the at least one second processingregion are separated by a gas curtain. A chamber exhaust system is influid communication with the chamber volume. The chamber exhaust systemincludes a chamber exhaust throttle valve downstream of the processingchamber. A first exhaust system is in fluid communication with the atleast one first processing region. The first exhaust system comprises afirst throttle valve and a first pressure gauge. A second exhaust systemis in fluid communication with the at least one second processingregion. The second exhaust system comprises a second throttle valve anda second pressure gauge. A controller is in communication with the firstexhaust system and the second exhaust system to control one or more ofthe first throttle valve and/or the second throttle valve in response tosignals from the first pressure gauge and/or the second pressure gauge.

Additional embodiments of the disclosure are directed to depositionsystems comprising a processing chamber. The processing chamber haswalls defining a chamber volume and includes a susceptor assembly and agas distribution assembly. The processing chamber has at least one firstprocessing region, at least one second processing region, at least onethird processing region and at least one fourth processing region. Eachof the processing regions is positioned between the gas distributionassembly and the susceptor assembly. Each of the processing regions areseparated from an adjacent processing region by a gas curtain. A chamberexhaust system is in fluid communication with the chamber volume. Thechamber exhaust system includes a chamber exhaust throttle valvedownstream of the processing chamber. A first exhaust system is in fluidcommunication with the at least one first processing region andcomprises a first throttle valve and a first pressure gauge. The secondexhaust system is in fluid communication with the at least one secondprocessing region and comprises a second throttle valve and a secondpressure gauge. A third exhaust system is in fluid communication withthe at least one third processing region and comprises a third throttlevalve and a third pressure gauge. A fourth exhaust system is in fluidcommunication with the at least one fourth processing region andcomprises a fourth throttle valve and a fourth pressure gauge. Acontroller is in communication with the first exhaust system, the secondexhaust system, the third exhaust system and the fourth exhaust systemto control the first throttle valve in response to signals from thefirst pressure gauge, the second throttle valve in response to signalsform the second pressure gauge, the third throttle valve in response tosignals from the third pressure gauge and the fourth throttle valve inresponse to signals from the fourth pressure gauge.

Further embodiments of the disclosure are directed to deposition systemscomprising a processing chamber. The processing chamber has wallsdefining a chamber volume and includes a susceptor assembly and a gasdistribution assembly. The processing chamber has at least one firstprocessing region, at least one second processing region, at least onethird processing region and at least one fourth processing region. Eachof the processing regions is positioned between the gas distributionassembly and the susceptor assembly. Each of the processing regions areseparated from an adjacent processing region by a gas curtain. A chamberexhaust system is in fluid communication with the chamber volume. Thechamber exhaust system includes a chamber exhaust throttle valvedownstream of the processing chamber. A first exhaust system is in fluidcommunication with the at least one first processing region andcomprises a first throttle valve and a first pressure gauge. The secondexhaust system is in fluid communication with the at least one secondprocessing region and comprises a second throttle valve and a secondpressure gauge. A third exhaust system is in fluid communication withthe at least one third processing region and comprises a third throttlevalve and a third pressure gauge. A fourth exhaust system is in fluidcommunication with the at least one fourth processing region andcomprises a fourth throttle valve and a fourth pressure gauge. Acontroller is in communication with the first exhaust system, the secondexhaust system, the third exhaust system and the fourth exhaust systemto control the first throttle valve in response to signals from thefirst pressure gauge, the second throttle valve in response to signalsform the second pressure gauge, the third throttle valve in response tosignals from the third pressure gauge and the fourth throttle valve inresponse to signals from the fourth pressure gauge. The first pressuregauge is an absolute gauge positioned downstream of the first throttlevalve and the second pressure gauge is an absolute gauge positioneddownstream of the second throttle valve. The third pressure gauge is adifferential gauge measuring a pressure differential relative to thefirst pressure gauge and the fourth pressure gauge is a differentialgauge measuring a pressure differential relative to the second pressuregauge.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 is a cross-sectional side view of a spatial atomic layerdeposition chamber in accordance with one or more embodiment of thedisclosure;

FIG. 2 is a schematic plan view of a substrate processing systemconfigured with four gas distribution assembly units with a loadingstation in accordance with one or more embodiments of the disclosure;

FIG. 3 shows a cross-sectional view of a processing chamber inaccordance with one or more embodiments of the disclosure;

FIG. 4 shows a perspective view of a susceptor assembly and gasdistribution assembly units in accordance with one or more embodimentsof the disclosure;

FIG. 5 shows a cross-sectional view of a processing chamber inaccordance with one or more embodiments of the disclosure;

FIG. 6 shows a schematic of a pie-shaped gas distribution assembly inaccordance with one or more embodiments of the disclosure;

FIG. 7 shows a schematic of a processing chamber in accordance with oneor more embodiment of the disclosure;

FIGS. 8A through 8C show schematic views of a processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 9 shows a schematic view of a processing chamber in accordance withone or more embodiment of the disclosure;

FIG. 10 shows a schematic view of a processing chamber in accordancewith one or more embodiment of the disclosure;

FIG. 11 shows a schematic view of a processing chamber in accordancewith one or more embodiment of the disclosure; and

FIG. 12 shows a schematic view of a processing chamber in accordancewith one or more embodiment of the disclosure.

DETAILED DESCRIPTION

Embodiments of the disclosure provide a substrate processing system forcontinuous substrate deposition to maximize throughput and improveprocessing efficiency and uniformity. The substrate processing systemcan also be used for pre-deposition and post-deposition substratetreatments. Embodiments of the disclosure are related to apparatus andmethods for increasing deposition uniformity in a batch processor.

As used in this specification and the appended claims, the term“substrate” and “wafer” are used interchangeably, both referring to asurface, or portion of a surface, upon which a process acts. It willalso be understood by those skilled in the art that reference to asubstrate can also refer to only a portion of the substrate, unless thecontext clearly indicates otherwise. For example, in spatially separatedALD, described with respect to FIG. 1, each precursor is delivered tothe substrate, but any individual precursor stream, at any given time,is only delivered to a portion of the substrate. Additionally, referenceto depositing on a substrate can mean both a bare substrate and asubstrate with one or more films or features deposited or formedthereon.

As used in this specification and the appended claims, the terms“reactive gas”, “process gas”, “precursor”, “reactant”, and the like,are used interchangeably to mean a gas that includes a species which isreactive in an atomic layer deposition process. For example, a first“reactive gas” may simply adsorb onto the surface of a substrate and beavailable for further chemical reaction with a second reactive gas.

Embodiments of the disclosure are directed to methods and apparatus tominimize gas phase mixing in spatial ALD through automatic control ofvacuum pumping for each chemical showerhead (channel) in each processregion of a batch processing chamber.

FIG. 1 is a schematic cross-sectional view of a portion of a processingchamber 20 in accordance with one or more embodiments of the disclosure.The processing chamber 20 is generally a sealable enclosure, which isoperated under vacuum or at least low pressure conditions. The chamber100 includes a gas distribution assembly 30 capable of distributing oneor more gases across the top surface 61 of a substrate 60. The gasdistribution assembly 30 can be any suitable assembly known to thoseskilled in the art, and specific gas distribution assemblies describedshould not be taken as limiting the scope of the disclosure. The outputface of the gas distribution assembly 30 faces the first surface 61 ofthe substrate 60.

Substrates for use with the embodiments of the disclosure can be anysuitable substrate. In some embodiments, the substrate is a rigid,discrete, generally planar substrate. As used in this specification andthe appended claims, the term “discrete” when referring to a substratemeans that the substrate has a fixed dimension. The substrate of one ormore embodiments is a semiconductor substrate, such as a 200 mm or 300mm diameter silicon substrate. In some embodiments, the substrate is oneor more of silicon, silicon germanium, gallium arsenide, galliumnitride, germanium, gallium phosphide, indium phosphide, sapphire andsilicon carbide.

The gas distribution assembly 30 comprises a plurality of gas ports totransmit one or more gas streams to the substrate 60 and a plurality ofvacuum ports disposed between each gas port to transmit the gas streamsout of the processing chamber 20. In the embodiment of FIG. 1, the gasdistribution assembly 30 comprises a first precursor injector 120, asecond precursor injector 130 and a purge gas injector 140. Theinjectors 120, 130, 140 may be controlled by a system computer (notshown), such as a mainframe, or by a chamber-specific controller, suchas a programmable logic controller. The precursor injector 120 injects acontinuous (or pulse) stream of a reactive precursor of compound A intothe processing chamber 20 through a plurality of gas ports 125. Theprecursor injector 130 injects a continuous (or pulse) stream of areactive precursor of compound B into the processing chamber 20 througha plurality of gas ports 135. The purge gas injector 140 injects acontinuous (or pulse) stream of a non-reactive or purge gas into theprocessing chamber 20 through a plurality of gas ports 145. The purgegas removes reactive material and reactive by-products from theprocessing chamber 20. The purge gas is typically an inert gas, such as,nitrogen, argon and helium. Gas ports 145 are disposed in between gasports 125 and gas ports 135 so as to separate the precursor of compoundA from the precursor of compound B, avoiding cross-contamination betweenthe precursors.

In another aspect, a remote plasma source (not shown) may be connectedto the precursor injector 120 and the precursor injector 130 prior toinjecting the precursors into the processing chamber 20. The plasma ofreactive species may be generated by applying an electric field to acompound within the remote plasma source. Any power source that iscapable of activating the intended compounds may be used. For example,power sources using DC, radio frequency (RF), and microwave (MW) baseddischarge techniques may be used. If an RF power source is used, it canbe either capacitively or inductively coupled. The activation may alsobe generated by a thermally based technique, a gas breakdown technique,a high energy light source (e.g., UV energy), or exposure to an x-raysource. Exemplary remote plasma sources are available from vendors suchas MKS Instruments, Inc. and Advanced Energy Industries, Inc.

The chamber 100 further includes a pumping system 150 connected to theprocessing chamber 20. The pumping system 150 is generally configured toevacuate the gas streams out of the processing chamber 20 through one ormore vacuum ports 155. The vacuum ports 155 are disposed between eachgas port so as to evacuate the gas streams out of the processing chamber20 after the gas streams react with the substrate surface and to furtherlimit cross-contamination between the precursors.

The chamber 100 includes a plurality of partitions 160 disposed on theprocessing chamber 20 between each port. A lower portion of eachpartition extends close to the first surface 61 of substrate 60, forexample, about 0.5 mm or greater from the first surface 61. In thismanner, the lower portions of the partitions 160 are separated from thesubstrate surface by a distance sufficient to allow the gas streams toflow around the lower portions toward the vacuum ports 155 after the gasstreams react with the substrate surface. Arrows 198 indicate thedirection of the gas streams. Since the partitions 160 operate as aphysical barrier to the gas streams, they also limit cross-contaminationbetween the precursors. The arrangement shown is merely illustrative andshould not be taken as limiting the scope of the disclosure. Thoseskilled in the art will understand that the gas distribution systemshown is merely one possible distribution system and the other types ofshowerheads and gas distribution assemblies may be employed.

Atomic layer deposition systems of this sort (i.e., where multiple gasesare separately flowed toward the substrate at the same time) arereferred to as spatial ALD. In operation, a substrate 60 is delivered(e.g., by a robot) to the processing chamber 20 and can be placed on ashuttle 65 before or after entry into the processing chamber. Theshuttle 65 is moved along the track 70, or some other suitable movementmechanism, through the processing chamber 20, passing beneath (or above)the gas distribution assembly 30. In the embodiment shown in FIG. 1, theshuttle 65 is moved in a linear path through the chamber. FIG. 2, asexplained further below, shows an embodiment in which wafers are movedin a circular path through a carousel processing system.

Referring back to FIG. 1, as the substrate 60 moves through theprocessing chamber 20, the first surface 61 of substrate 60 isrepeatedly exposed to the reactive gas A coming from gas ports 125 andreactive gas B coming from gas ports 135, with the purge gas coming fromgas ports 145 in between. Injection of the purge gas is designed toremove unreacted material from the previous precursor prior to exposingthe substrate surface 110 to the next precursor. After each exposure tothe various gas streams (e.g., the reactive gases or the purge gas), thegas streams are evacuated through the vacuum ports 155 by the pumpingsystem 150. Since a vacuum port may be disposed on both sides of eachgas port, the gas streams are evacuated through the vacuum ports 155 onboth sides. Thus, the gas streams flow from the respective gas portsvertically downward toward the first surface 61 of the substrate 60,across the substrate surface 110 and around the lower portions of thepartitions 160, and finally upward toward the vacuum ports 155. In thismanner, each gas may be uniformly distributed across the substratesurface 110. Arrows 198 indicate the direction of the gas flow.Substrate 60 may also be rotated while being exposed to the various gasstreams. Rotation of the substrate may be useful in preventing theformation of strips in the formed layers. Rotation of the substrate canbe continuous or in discrete steps and can occur while the substrate ispassing beneath the gas distribution assembly 30 or when the substrateis in a region before and/or after the gas distribution assembly 30.

In the linear system of FIG. 1, sufficient space is generally providedafter the gas distribution assembly 30 to ensure complete exposure tothe last gas port. Once the substrate 60 has completely passed beneaththe gas distribution assembly 30, the first surface 61 has completelybeen exposed to every gas port in the processing chamber 20. Thesubstrate can then be transported back in the opposite direction orforward. If the substrate 60 moves in the opposite direction, thesubstrate surface may be exposed again to the reactive gas A, the purgegas, and reactive gas B, in reverse order from the first exposure.

The extent to which the substrate surface 110 is exposed to each gas maybe determined by, for example, the flow rates of each gas coming out ofthe gas port and the rate of movement of the substrate 60. In oneembodiment, the flow rates of each gas are controlled so as not toremove adsorbed precursors from the substrate surface 61. The widthbetween each partition, the number of gas ports disposed on theprocessing chamber 20, and the number of times the substrate is passedacross the gas distribution assembly may also determine the extent towhich the substrate surface 61 is exposed to the various gases.Consequently, the quantity and quality of a deposited film may beoptimized by varying the above-referenced factors.

Although description of the process has been made with the gasdistribution assembly 30 directing a flow of gas downward toward asubstrate positioned below the gas distribution assembly, it will beunderstood that this orientation can be different. In some embodiments,the gas distribution assembly 30 directs a flow of gas upward toward asubstrate surface. As used in this specification and the appendedclaims, the term “passed across” means that the substrate has been movedfrom one side of the gas distribution assembly to the other side so thatthe entire surface of the substrate is exposed to each gas stream fromthe gas distribution plate. Absent additional description, the term“passed across” does not imply any particular orientation of gasdistribution assemblies, gas flows or substrate positions.

In some embodiments, the shuttle 65 is a susceptor that can carrymultiple substrates. Generally, the susceptor helps to form a uniformtemperature across the substrate. The susceptor 66 is movable in bothdirections (left-to-right and right-to-left, relative to the arrangementof FIG. 1) or in a circular direction (relative to FIG. 2). Thesusceptor has a top surface for carrying the substrate and may beheated. As an example, the susceptor may be heated by radiant heat lamps90, a heating plate, resistive coils, or other heating devices, disposedunderneath the susceptor or within the susceptor body.

FIG. 1 shows a cross-sectional view of a processing chamber in which theindividual gas ports are shown. This embodiment can be either a linearprocessing system in which the width of the individual gas ports issubstantially the same across the entire width of the gas distributionplate, or a pie-shaped segment in which the individual gas ports changewidth to conform to the pie shape, as described further with respect toFIG. 6.

Processing chambers having multiple gas injectors can be used to processmultiple wafers simultaneously so that the wafers experience the sameprocess flow. For example, as shown in FIG. 2, the processing chamber100 has four gas distribution assemblies 30 and four substrates 60. Atthe outset of processing, the substrates 60 can be positioned betweenthe gas distribution assemblies 30. Rotating the susceptor 66 of thecarousel by 45° will result in each substrate 60 being moved to aninjector assembly 30 for film deposition. This is the position shown inFIG. 2. An additional 45° rotation would move the substrates 60 awayfrom the gas distribution assemblies 30. With spatial ALD injectors, afilm is deposited on the wafer during movement of the wafer relative tothe injector assembly. In some embodiments, the susceptor 66 is rotatedso that the substrates 60 do not stop beneath the gas distributionassemblies 30. The number of substrates 60 and gas distributionassemblies 30 can be the same or different. In some embodiments, thereis the same number of wafers being processed as there are gasdistribution assemblies. In one or more embodiments, the number ofwafers being processed are an integer multiple of the number of gasdistribution assemblies. For example, if there are four gas distributionassemblies, there are 4x wafers being processed, where x is an integervalue greater than or equal to one.

The processing chamber 100 shown in FIG. 2 is merely representative ofone possible configuration and should not be taken as limiting the scopeof the disclosure. Here, the processing chamber 100 includes a pluralityof gas distribution assemblies 30. In the embodiment shown, there arefour gas distribution assemblies 30 evenly spaced about the processingchamber 100. The processing chamber 100 shown is octagonal, however, itwill be understood by those skilled in the art that this is one possibleshape and should not be taken as limiting the scope of the disclosure.Additionally, each segment can be configured to deliver gases in aspatial type arrangement with multiple different reactive gases flowingfrom the same segment or configured to deliver a single reactive gas ora mixture of reactive gases.

The processing chamber 100 includes a substrate support apparatus, shownas a round susceptor 66 or susceptor assembly. The substrate supportapparatus, or susceptor 66, is capable of moving a plurality ofsubstrates 60 beneath each of the gas distribution assemblies 30. A loadlock 82 might be connected to a side of the processing chamber 100 toallow the substrates 60 to be loaded/unloaded from the chamber 100.

The processing chamber 100 may include a plurality, or set, of firsttreatment stations 80 positioned between any or each of the plurality ofgas distribution assemblies 30. In some embodiments, each of the firsttreatment stations 80 provides the same treatment to a substrate 60.

The number of treatment stations and the number of different types oftreatment stations can vary depending on the process. For example, therecan be one, two, three, four, five, six, seven or more treatmentstations positioned between the gas distribution assemblies 30. Eachtreatment stations can independently provide a different treatment fromevery other set of treatments station, or there can be a mixture of thesame type and different types of treatments. In some embodiments, one ormore of the individual treatments stations provides a differenttreatment than one or more of the other individual treatment stations.While the embodiment shown in FIG. 2 shows four gas distributionassemblies with spaces between which can include some type of treatmentstation, those skilled in the art will understand that the processingchamber can readily be incorporated with eight gas distributionassemblies with the gas curtains between.

Treatment stations can provide any suitable type of treatment to thesubstrate, film on the substrate or susceptor assembly. For example, UVlamps, flash lamps, plasma sources and heaters. The wafers are thenmoved between positions with the gas distribution assemblies 30 to aposition with, for example, a showerhead delivering plasma to the wafer.The plasma station being referred to as a treatment station 80. In oneor more example, silicon nitride films can be formed with plasmatreatment after each deposition layer. As the ALD reaction is,theoretically, self-limiting as long as the surface is saturated,additional exposure to the deposition gas will not cause damage to thefilm.

Rotation of the carousel can be continuous or discontinuous. Incontinuous processing, the wafers are constantly rotating so that theyare exposed to each of the injectors in turn. In discontinuousprocessing, the wafers can be moved to the injector region and stopped,and then to the region 84 between the injectors and stopped. Forexample, the carousel can rotate so that the wafers move from aninter-injector region across the injector (or stop adjacent theinjector) and on to the next inter-injector region where the substratecan pause again. Pausing between the injectors may provide time foradditional processing steps between each layer deposition (e.g.,exposure to plasma).

In some embodiments, the processing chamber comprises a plurality of gascurtains 40. Each gas curtain 40 creates a barrier to prevent, orminimize, the movement of processing gases from the gas distributionassemblies 30 from migrating from the gas distribution assembly regionsand gases from the treatment stations 80 from migrating from thetreatment station regions. The gas curtain 40 can include any suitablecombination of gas and vacuum streams which can isolate the individualprocessing sections from the adjacent sections. In some embodiments, thegas curtain 40 is a purge (or inert) gas stream. In one or moreembodiments, the gas curtain 40 is a vacuum stream that removes gasesfrom the processing chamber. In some embodiments, the gas curtain 40 isa combination of purge gas and vacuum streams so that there are, inorder, a purge gas stream, a vacuum stream and a purge gas stream. Inone or more embodiments, the gas curtain 40 is a combination of vacuumstreams and purge gas streams so that there are, in order, a vacuumstream, a purge gas stream and a vacuum stream. The gas curtains 40shown in FIG. 2 are positioned between each of the gas distributionassemblies 30 and treatment stations 80, but it will be understood thatthe curtains can be positioned at any point or points along theprocessing path.

FIG. 3 shows an embodiment of a processing chamber 200 including a gasdistribution assembly 220, also referred to as the injectors, and asusceptor assembly 230. In this embodiment, the susceptor assembly 230is a rigid body. The rigid body of some embodiments has a drooptolerance no larger than 0.05 mm. Actuators 232 may be placed, forexample, at three locations at the outer diameter region of thesusceptor assembly 230. As used in this specification and the appendedclaims, the terms “outer diameter” and “inner diameter” refer to regionsnear the outer peripheral edge and the inner edge, respectively. Theouter diameter is not to a specific position at the extreme outer edge(e.g., near shaft 240) of the susceptor assembly 230, but is a regionnear the outer edge 231 of the susceptor assembly 230. This can be seenin FIG. 3 from the placement of the actuators 232. The number ofactuators 232 can vary from one to any number that will fit within thephysical space available. Some embodiments have two, three, four or fivesets of actuators 232 positioned in the outer diameter region 231. Asused in this specification and the appended claims, the term “actuator”refers to any single or multi-component mechanism which is capable ofmoving the susceptor assembly 230, or a portion of the susceptorassembly 230, toward or away from the gas distribution assembly 220. Forexample, actuators 232 can be used to ensure that the susceptor assembly230 is substantially parallel to the gas distribution assembly 220. Asused in this specification and the appended claims, the term“substantially parallel” used in this regard means that the parallelismof the components does not vary by more than 5% relative to the distancebetween the components.

Once pressure is applied to the susceptor assembly 230 from theactuators 232, the susceptor assembly 230 can be levelled. As thepressure is applied by the actuators 232, the gap 210 distance can beset to be within the range of about 0.1 mm to about 2.0 mm, or in therange of about 0.2 mm to about 1.8 mm, or in the range of about 0.3 mmto about 1.7 mm, or in the range of about 0.4 mm to about 1.6 mm, or inthe range of about 0.5 mm to about 1.5 mm, or in the range of about 0.6mm to about 1.4 mm, or in the range of about 0.7 mm to about 1.3 mm, orin the range of about 0.8 mm to about 1.2 mm, or in the range of about0.9 mm to about 1.1 mm, or about 1 mm.

The susceptor assembly 230 is positioned beneath the gas distributionassembly 220. The susceptor assembly 230 includes a top surface 241 and,optionally, at least one recess 243 in the top surface 241. The recess243 can be any suitable shape and size depending on the shape and sizeof the wafers 260 being processed. In the embodiment shown, the recess243 has a step region around the outer peripheral edge of the recess243. The steps can be sized to support the outer peripheral edge of thewafer 260. The amount of the outer peripheral edge of the wafer 260 thatis supported by the steps can vary depending on, for example, thethickness of the wafer and the presence of features already present onthe back side of the wafer.

In some embodiments, as shown in FIG. 3, the recess 243 in the topsurface 241 of the susceptor assembly 230 is sized so that a wafer 260supported in the recess 243 has a top surface 261 substantially coplanarwith the top surface 241 of the susceptor assembly 230. As used in thisspecification and the appended claims, the term “substantially coplanar”means that the top surface of the wafer and the top surface of thesusceptor assembly are coplanar within ±0.2 mm. In some embodiments, thetop surfaces are coplanar within ±0.15 mm, ±0.10 mm or ±0.05 mm.

The susceptor assembly 230 of FIG. 3 includes a support post 240 whichis capable of lifting, lowering and rotating the susceptor assembly 230.The susceptor assembly 230 may include a heater, or gas lines, orelectrical components within the center of the support post 240. Thesupport post 240 may be the primary means of increasing or decreasingthe gap between the susceptor assembly 230 and the gas distributionassembly 220, moving the susceptor assembly 230 into rough position. Theactuators 232 can then make micro-adjustments to the position of thesusceptor assembly to create the predetermined gap.

The processing chamber 100 shown in FIG. 3 is a carousel-type chamber inwhich the susceptor assembly 230 can hold a plurality of wafers 260. Thegas distribution assembly 220 may include a plurality of separateinjector units 221, each injector unit 221 being capable of depositing afilm or part of a film on the wafer 260, as the wafer is moved beneaththe injector unit 221. FIG. 4 shows a perspective view of acarousel-type processing chamber 200. Two pie-shaped injector units 221are shown positioned on approximately opposite sides of and above thesusceptor assembly 230. This number of injector units 221 is shown forillustrative purposes only. It will be understood that more or lessinjector units 221 can be included. In some embodiments, there are asufficient number of pie-shaped injector units 221 to form a shapeconforming to the shape of the susceptor assembly 230. In someembodiments, each of the individual pie-shaped injector units 221 may beindependently moved, removed and/or replaced without affecting any ofthe other injector units 221. For example, one segment may be raised topermit a robot to access the region between the susceptor assembly 230and gas distribution assembly 220 to load/unload wafers 260.

FIG. 5 shows another embodiment of the disclosure in which the susceptorassembly 230 is not a rigid body. In some embodiments, the susceptorassembly 230 has a droop tolerance of not more than about 0.1 mm, or notmore than about 0.05 mm, or not more than about 0.025 mm, or not morethan about 0.01 mm. Here, there are actuators 232 placed at the outerdiameter region 231 and at the inner diameter region 239 of thesusceptor assembly 230. The actuators 232 can be positioned at anysuitable number of places around the inner and outer periphery of thesusceptor assembly 230. In some embodiments, the actuators 232 areplaced at three locations at both the outer diameter region 231 and theinner diameter region 239. The actuators 232 at both the outer diameterregion 231 and the inner diameter region 239 apply pressure to thesusceptor assembly 230.

FIG. 6 shows a gas distribution assembly 220 in accordance with one ormore embodiment of the disclosure. The front face 225 of a portion orsegment of a generally circular gas distribution assembly 220 is shown.As used in this specification and the appended claims, the term“generally circular” means that the overall shape of the component doesnot have any angles less than 80°. Thus, generally circular can have anyshape including square, pentagonal, hexagonal, heptagonal, octagonal,etc. Generally circular should not be taken as limiting the shape to acircle or perfect polygon, but can also include oval and imperfectpolygons. The gas distribution assembly 220 includes a plurality ofelongate gas ports 125, 135, 145 in the front face 225. The gas portsextend from the inner diameter region 239 to an outer diameter region231 of the gas distribution assembly 220.

The shape or aspect ratio of the individual ports can be proportionalto, or different from, the shape or aspect ratio of the gas distributionassembly segment. In some embodiments, the individual ports are shapedso that each point of a wafer passing across the gas distributionassembly 220 following path 272 would have about the same residence timeunder each gas port. The path of the substrates can be perpendicular tothe gas ports. In some embodiments, each of the gas distributionassemblies comprises a plurality of elongate gas ports which extend in adirection substantially perpendicular to the path traversed by asubstrate. As used in this specification and the appended claims, theterm “substantially perpendicular” means that the general direction ofmovement is approximately perpendicular to the axis of the gas ports.For a pie-shaped gas port, the axis of the gas port can be considered tobe a line defined as the mid-point of the width of the port extendingalong the length of the port. Each of the individual pie-shaped segmentscan be configured to deliver a single reactive gas or multiple reactivegases separated spatially or in combination (e.g., as in a typical CVDprocess).

The plurality of gas ports include a first reactive gas port 125 todeliver a first reactive gas to the processing chamber and a purge gasport 145 to deliver a purge gas to the processing chamber. Theembodiment shown in FIG. 6 also includes a second reactive gas port 135to deliver a second reactive gas to the processing chamber.

A vacuum port 155 separates the first reactive gas port 125 and secondreactive gas port 135 from the adjacent purge gas ports 145. Stateddifferently, the vacuum port is positioned between the first reactivegas port 125 and the purge gas port 145 and between the second reactivegas port 135 and the purge gas port 145. The vacuum ports evacuate gasesfrom the processing chamber. In the embodiment shown in FIG. 6, thevacuum ports 155 extend around all sides of the reactive gas ports sothat there is a portion of the vacuum port 155 on the inner peripheraledge 227 and outer peripheral edge 228 of each of the first reactive gasport 125 and second reactive gas port 135.

In use, a substrate is passed adjacent the gas distribution plate 220along path 272. In transit, the substrate will encounter gas flows,either flowing into the chamber or out of the chamber, in order, a purgegas port 145, a first vacuum port 155 a, a first reactive gas port 125,a second vacuum port 155 b, a purge gas port 145, a first vacuum port155 a, a second reactive gas port 135 and a second vacuum port 155 b.The first vacuum port 155 a and second vacuum port 155 b are shownconnected as a single vacuum port 155.

FIG. 7 shows a schematic of a spatial atomic layer deposition chamber inaccordance with one or more embodiment of the disclosure. As can beseen, there is one pump for chamber pumping and two other pumps forinjector (gas distribution assembly) pumping. Additionally, one inertpurge gas goes to the chamber volume and several different gases (inertgases and reactive chemicals) go to the gas distribution assembly.

The chamber purge 205 flows an inert purge gas into the chamber topressurize the chamber space outside of the reaction area locatedbetween the susceptor assembly and the gas distribution assembly. Achamber throttle valve is used to control the pressure of the chamber.The pressure in the chamber can be measured using gauge 206.

Chemical precursor A and B flow into the chamber through independentchemical channels in the injector (gas distribution assembly). Eachchemical channel is surrounded by vacuum pumping channels. An inert gaspurge curtain is positioned between chemical channels to maintainseparation of the reactive gases.

The throttle valve control for pumping channel A and B may use forelinepressure control, which means that the throttle valves adjust angles toreach the pressure setpoint at downstream of the throttle valve. This isthe opposite of a typical pressure control mechanism where pressureupstream of the throttle valve is controlled. The downstream/forelinepressure control for A and B pumping lines may help ensure that theamount of gases pumped out of each pumping channel is equal to the gasamount flowing into that channel and may include part of the inertseparation gas. In total, the amount of gases flowing in the chamberthrough the gas distribution assembly should be pumped out of thechamber by pumps A and B.

A typical relationship between the foreline pressure reading and theactual gas flowing into that pump is basically a straight line. Thiscoincides with the law of conservation of mass. Theoretically, the gasthroughput (Q, Torr L/s) to the pump has a linear relationship with thepump foreline pressure (P, torr) and the slope is the pumping speed (C,L/s), where Q=C×P. Practically, the curve shape will depend on thevacuum pump speed, gas species, the physical location of the forelinepressure gauge, and the real gas temperature as detected by forelinepressure gauge, etc. One or more embodiments of the disclosureadvantageously provide consistent gas pressure control. In someembodiments, the processing system automatically monitors the data curvefor different chamber conditions and controls the foreline pressurebased on the real flow of gases. One or more embodiments advantageouslyprovide control of the foreline pressure to manage gas pressure in theprocessing regions of the processing chamber. One or more embodiments ofthe disclosure advantageously provide control of the gas flows tominimize gas phase reactions.

Still referring to FIG. 7, one or more embodiments of the disclosure aredirected to processing chambers 200 having walls 201 defining a chambervolume 202. The embodiment shown in FIG. 7 is a schematic representationof a generally circular processing system, like that shown in FIG. 4.The processing chamber 200 includes a susceptor assembly 230 and a gasdistribution assembly 220. There is at least one first processing region321 and at least one second processing region 322. As shown in FIG. 7,the first processing region 321 is associated with the first processgas, denoted A, and the second processing region 322 is associated withthe second process gas, denoted B. Those skilled in the art willunderstand that this is merely illustrative of one possible arrangementand should not be taken as limiting the scope of the disclosure. Each ofthe first processing region 321 and second processing region 322 arepositioned between the gas distribution assembly 220 and the susceptorassembly 230. Each of the first processing region 321 and secondprocessing region 322 are separated by a gas curtain 327. The gascurtain can be any suitable combination of gases and vacuum that preventor minimize mixing of the first process gas A and the second process gasB.

A chamber exhaust system 340 is in fluid communication with the chambervolume 202. The chamber exhaust system 340 maintains a reduced pressurestate in the chamber volume. The pressure in the chamber volume 202 canbe the same as, or different from the pressure in the first processingregion 321 and the second processing region 322. The chamber exhaustsystem 340 includes a chamber exhaust throttle valve 341 positioneddownstream of the processing chamber 200. As used herein, the terms“upstream” and “downstream” refer to relative directions according tothe flow of an exhaust gas stream from the interior of the processingchamber. Downstream of the chamber exhaust throttle valve 341 is avacuum source 399. The vacuum source 399 can be any suitable vacuumsource including, but not limited to, a house vacuum or an individualvacuum pump.

The processing chamber includes a first exhaust system 350 in fluidcommunication with the at least one first processing region 321. Thefirst exhaust system 350 shown in FIG. 7 includes a vacuum port 155 thatextends on either side of the first process gas A port 125. As shown inFIG. 6, the vacuum port can extend around all four sides of the processgas A port 125. The first exhaust system 350 comprises a first throttlevalve 351 and a first pressure gauge 352. The embodiment shown in FIG. 7has the first pressure gauge 352 positioned downstream of the firstthrottle valve 351, but this is merely representative of one possiblearrangement. The first exhaust system 350 connects to a suitable vacuumsource which can be the same as vacuum source 399 or different.

The processing chamber 200 includes a second exhaust system 360 in fluidcommunication with the at least one second processing region 322. Thesecond exhaust system 360 shown in FIG. 7 includes a vacuum port 155that extends on either side of the second process gas B port 135. Asshown in FIG. 6, the vacuum port can extend around all four sides of theprocess gas B port 135. The second exhaust system 360 comprises a secondthrottle valve 361 and a second pressure gauge 362. The embodiment shownin FIG. 7 has the second pressure gauge 362 positioned downstream of thesecond throttle valve 361, but this is merely representative of onepossible arrangement. The second exhaust system 360 connects to asuitable vacuum source which can be the same as vacuum source 399 ordifferent.

A controller 390 is in communication with the first exhaust system 350and the second exhaust system 360. The controller 390 can control thefirst throttle valve 351 in response to signals from the first pressuregauge 352 and can control the second throttle valve 361 in response tosignals from the second pressure gauge 362. In some embodiments, thecontroller 390 maintains separation of gases in the first processingregion 321 and the second processing region 322 by opening/closing thethrottle valves in response to measurements from the pressure gauges. Acontroller 390 can be any suitable controller comprising one or more ofhardware, firmware and/or software. In some embodiments, the controller390 includes a computer with one or more of a central processing unit,memory, storage and/or circuits configured to communicate with thephysical components associated with the processing chamber. For example,the computer may include computer readable instructions on computerreadable media that allows a user to input processing parametersincluding, but not limited to, gas pressures, flow rates and pressuredifferential tolerances.

FIG. 8A shows a schematic representation of a processing chamber inaccordance with FIG. 7. The first process gas A and second process gas Bare schematically represented by a square indicating the boundaries ofthe gas ports 125, 135. A vacuum port 155, also represented as a square,is shown around each of the gas ports 125, 135. This schematicrepresentation is merely exemplary and should not be taken as implyingor limiting the shape or width of the gas ports or vacuum ports. Theembodiment shown in FIG. 8A has the first pressure gauge 352 positioneddownstream of the first throttle valve 251 and the second pressure gauge362 positioned downstream of the second throttle valve 361. While notshown, it will be understood that a controller, like that of FIG. 7 canalso be included.

In the embodiments shown in FIGS. 7 and 8A, the controller 390 monitorsthe pressure in the exhaust line downstream of the throttle valves 351,361. If the pressure in the exhaust line is too low, the pressure in theprocess region is too high and the controller will cause the appropriatethrottle valve to open further. If the pressure in the exhaust line istoo high, the pressure in the process region is too low and thecontroller will partially close the appropriate throttle valve. Thecontroller 390 may also close the throttle valves completely to isolatethe chamber volume 202.

The embodiment shown in FIG. 8B has the first pressure gauge 352positioned upstream of the first throttle valve 351 and the secondpressure gauge 362 positioned upstream of the second throttle valve 361.In the embodiment shown in FIG. 8B, the controller monitors the pressurein the exhaust line upstream of the throttle valves. The pressure gaugeshere are positioned on the processing chamber side of the throttlevalve. If the pressure in the exhaust line is too low, the pressure inthe process region is too low and the controller will cause theappropriate throttle valve to move toward the closed position. If thepressure in the exhaust line is too high, the pressure in the processregion is too high and the controller will cause the appropriatethrottle valve to open further.

The pressure gauges employed can be any suitable pressure gauges. Insome embodiments, the pressure gauges are absolute gauges referenced toeither a perfect vacuum or to conditions outside of the processingchamber. In some embodiments, differential pressure gauges are used. Adifferential pressure gauge measures the difference in pressure betweentwo points.

In some embodiments, the pressure gauges are upstream of the controllerdetermines the difference in pressure measured by the second pressuregauge relative to the first pressure gauge. In one or more embodiments,as shown in FIG. 8C, the first pressure gauge is an absolute gauge andthe second pressure gauge is a differential pressure gauge measuringpressure relative to the pressure in the first exhaust system.

In some embodiments, the controller 390 adjust the gas flow in theprocessing regions so that the absolute pressure differential betweenthe first processing region 321 and the second processing region 322 isup to about 5 torr. In some embodiments, the controller 390 isconfigured to adjust the gas flow in one or more of the processingregions so that the difference between the pressures, eitherdifferential or absolute, is less than or equal to about 5 torr, 4 torr,3 torr or 2 torr.

FIG. 9 shows another embodiment of a processing chamber 200. Theprocessing chamber 200 includes a first processing region 321 adjacentthe first process gas A port, a second processing region 322 adjacentthe second process gas B port, a third processing region 323 adjacent athird process gas C port and a fourth processing region 324 adjacent afourth process gas D port. The processing regions are described as beingadjacent the respective gas ports but it will be understood that theprocess region is between the gas distribution assembly and thesusceptor assembly. Each of the at least one first processing region321, the at least one second processing region 322, the at least onethird processing region 323 and the at least one fourth processingregion 324 are separated by gas curtains 325.

A third exhaust system 370 is in fluid communication with the at leastone third processing region 323. The third exhaust system 370 comprisinga third throttle valve 371 and a third pressure gauge 372. A fourthexhaust system 380 is in fluid communication with the fourth processingregion 324. The fourth exhaust system 380 includes a fourth throttlevalve 381 and a fourth pressure gauge 382.

The controller (not shown) is in communication with the first exhaustsystem 350, the second exhaust system 360, the third exhaust system 370and the fourth exhaust system 380 to control throttle valves 351, 361,371, 381 in response to signals from the first pressure gauge 352, thesecond pressure gauge 362, the third pressure gauge 372 and the fourthpressure gauge 382.

In the embodiment shown in FIG. 9, the first pressure gauge 352 isdownstream of the first throttle valve 351, the second pressure gauge362 is downstream of the second throttle valve 361, the third pressuregauge 372 is downstream of the third throttle valve 371 and the fourthpressure gauge 382 is downstream of the fourth throttle valve 381. Inthe embodiment shown in FIG. 10, the first pressure gauge 352 isupstream of the first throttle valve 351, the second pressure gauge 362is upstream of the second throttle valve 361, the third pressure gauge372 is upstream of the third throttle valve 371 and the fourth pressuregauge 382 is upstream of the fourth throttle valve 381.

In some embodiments, each of the first pressure gauge 352, the secondpressure gauge 362, the third pressure gauge 372 and the fourth pressuregauge 382 are absolute gauges. In one or more embodiments, thecontroller 390 determines a difference in pressure measured by one ormore of the second pressure gauge 362, the third pressure gauge 372 orthe fourth pressure gauge 382 relative to the first pressure gauge 352.

FIG. 11 shows another embodiment of the disclosure in which the firstpressure gauge 352 is an absolute gauge positioned upstream of the firstthrottle valve 351 and each of the second pressure gauge 362, the thirdpressure gauge 372 and the fourth pressure gauge 382 are differentialpressure gauges that measure the pressure differential relative to thefirst pressure gauge.

FIG. 12 shows another embodiment of the disclosure in which the firstpressure gauge 352 is an absolute gauge positioned downstream of thefirst throttle valve 351 and the second pressure gauge 362 is anabsolute gauge positioned downstream of the second throttle valve 361.The third pressure gauge 372 is a differential gauge measuring apressure differential relative to the first pressure gauge 352. Thefourth pressure gauge 382 is a differential gauge measuring a pressuredifferential relative to the second pressure gauge 362. Embodiments ofthis sort may be, but are not necessarily, used where the first processgas and the third process gas are the same and where the second processgas and the fourth process gas are the same.

The controller 390 of some embodiments controls all of the throttlevalves for each of the processing regions and for the processing volume.In some embodiments, there are four different processing regions (i.e.,four different processing conditions) and the controller 390 maintainsthe pressure in all four processing regions and the processing chambervolume so that each region is isolated from adjacent regions by a gascurtain.

The position of the pressure gauges can be varied to before (upstreamof) or after (downstream of) the throttle valves. When the pressuregauge is before the throttle valve, in some embodiments, the pressuregauge is positioned as close to the processing region as possible.

The exposure to the first process conditions and the second processconditions can be repeated sequentially to grow a film of predeterminedthickness. For example, the batch processing chamber may contain twosections with the first process conditions and two sections of thesecond process conditions in alternating pattern, so that rotation ofthe substrate around the central axis of the processing chamber causesthe surface to be sequentially and repeatedly exposed to the first andsecond process conditions so that each exposure causes the filmthickness (for depositions) to grow.

In some embodiments, one or more layers may be formed during a plasmaenhanced atomic layer deposition (PEALD) process. The use of plasma mayprovide sufficient energy to promote a species into the excited statewhere surface reactions become favorable and likely. Introducing theplasma into the process can be continuous or pulsed. In someembodiments, sequential pulses of precursors (or reactive gases) andplasma are used to process a layer. In some embodiments, the reagentsmay be ionized either locally (i.e., within the processing area) orremotely (i.e., outside the processing area). In some embodiments,remote ionization can occur upstream of the deposition chamber such thations or other energetic or light emitting species are not in directcontact with the depositing film. In some PEALD processes, the plasma isgenerated external from the processing chamber, such as by a remoteplasma generator system. The plasma may be generated via any suitableplasma generation process or technique known to those skilled in theart. For example, plasma may be generated by one or more of a microwave(MW) frequency generator or a radio frequency (RF) generator. Thefrequency of the plasma may be tuned depending on the specific reactivespecies being used. Suitable frequencies include, but are not limitedto, 2 MHz, 13.56 MHz, 40 MHz, 60 MHz and 100 MHz. Although plasmas maybe used during the deposition processes disclosed herein, it should benoted that plasmas may not be required. Indeed, other embodiments relateto deposition processes under very mild conditions without a plasma.

According to one or more embodiments, the substrate is subjected toprocessing prior to and/or after forming the layer. This processing canbe performed in the same chamber or in one or more separate processingchambers. In some embodiments, the substrate is moved from the firstchamber to a separate, second chamber for further processing. Thesubstrate can be moved directly from the first chamber to the separateprocessing chamber, or the substrate can be moved from the first chamberto one or more transfer chambers, and then moved to the predeterminedseparate processing chamber. Accordingly, the processing apparatus maycomprise multiple chambers in communication with a transfer station. Anapparatus of this sort may be referred to as a “cluster tool” or“clustered system”, and the like.

Generally, a cluster tool is a modular system comprising multiplechambers which perform various functions including substratecenter-finding and orientation, degassing, annealing, deposition and/oretching. According to one or more embodiments, a cluster tool includesat least a first chamber and a central transfer chamber. The centraltransfer chamber may house a robot that can shuttle substrates betweenand among processing chambers and load lock chambers. The transferchamber is typically maintained at a vacuum condition and provides anintermediate stage for shuttling substrates from one chamber to anotherand/or to a load lock chamber positioned at a front end of the clustertool. Two well-known cluster tools which may be adapted for the presentdisclosure are the Centura® and the Endura®, both available from AppliedMaterials, Inc., of Santa Clara, Calif. However, the exact arrangementand combination of chambers may be altered for purposes of performingspecific steps of a process as described herein. Other processingchambers which may be used include, but are not limited to, cyclicallayer deposition (CLD), atomic layer deposition (ALD), chemical vapordeposition (CVD), physical vapor deposition (PVD), etch, pre-clean,chemical clean, thermal treatment such as RTP, plasma nitridation,degas, orientation, hydroxylation and other substrate processes. Bycarrying out processes in a chamber on a cluster tool, surfacecontamination of the substrate with atmospheric impurities can beavoided without oxidation prior to depositing a subsequent film.

According to one or more embodiments, the substrate is continuouslyunder vacuum or “load lock” conditions, and is not exposed to ambientair when being moved from one chamber to the next. The transfer chambersare thus under vacuum and are “pumped down” under vacuum pressure. Inertgases may be present in the processing chambers or the transferchambers. In some embodiments, an inert gas is used as a purge gas toremove some or all of the reactants after forming the layer on thesurface of the substrate. According to one or more embodiments, a purgegas is injected at the exit of the deposition chamber to preventreactants from moving from the deposition chamber to the transferchamber and/or additional processing chamber. Thus, the flow of inertgas forms a curtain at the exit of the chamber.

During processing, the substrate can be heated or cooled. Such heatingor cooling can be accomplished by any suitable means including, but notlimited to, changing the temperature of the substrate support (e.g.,susceptor) and flowing heated or cooled gases to the substrate surface.In some embodiments, the substrate support includes a heater/coolerwhich can be controlled to change the substrate temperatureconductively. In one or more embodiments, the gases (either reactivegases or inert gases) being employed are heated or cooled to locallychange the substrate temperature. In some embodiments, a heater/cooleris positioned within the chamber adjacent the substrate surface toconvectively change the substrate temperature.

The substrate can also be stationary or rotated during processing. Arotating substrate can be rotated continuously or in discreet steps. Forexample, a substrate may be rotated throughout the entire process, orthe substrate can be rotated by a small amount between exposures todifferent reactive or purge gases. Rotating the substrate duringprocessing (either continuously or in steps) may help produce a moreuniform deposition or etch by minimizing the effect of, for example,local variability in gas flow geometries.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. An exhaust system comprising: a first exhaustsystem in fluid communication with a first processing region of aprocessing chamber, the first exhaust system comprising a first throttlevalve and a first pressure gauge; a second exhaust system in fluidcommunication with a second processing region of the processing chamber,the second exhaust system comprising a second throttle valve and asecond pressure gauge; and a controller in communication with the firstexhaust system and the second exhaust system to control the firstthrottle valve or the second throttle valve in response to signals fromthe first pressure gauge or the second pressure gauge, the controllerconfigured to ensure that an amount of gas supplied to each processingregion is equal to an amount of gas removed from each processing region.2. The exhaust system of claim 1, wherein at least one of the firstpressure gauge and the second pressure gauge is upstream of a respectivethrottle valve.
 3. The exhaust system of claim 1, wherein at least oneof the first pressure gauge and the second pressure gauge is downstreamof a respective throttle valve.
 4. The exhaust system of claim 1,wherein the first pressure gauge is upstream of the first throttle valveand the second pressure gauge is upstream of the second throttle valve.5. The exhaust system of claim 1, wherein the first pressure gauge isdownstream of the first throttle valve and the second pressure gauge isdownstream of the second throttle valve.
 6. The exhaust system of claim1, wherein the first pressure gauge and the second pressure gauge areabsolute gauges.
 7. The exhaust system of claim 1, wherein the firstpressure gauge is an absolute gauge, and the second pressure gauge is adifferential pressure gauge.
 8. The exhaust system of claim 1, whereinan absolute pressure differential between the first processing regionand the second processing region is less than or equal to about 5 torr.9. The exhaust system of claim 1, wherein the controller controls thefirst throttle valve and the second throttle valve in response tosignals from the first pressure gauge and the second pressure gauge,respectively.
 10. The exhaust system of claim 1, wherein the controlleris further configured to maintain separation of gases in the firstprocessing region and the second processing region.
 11. The exhaustsystem of claim 1, further comprising a chamber exhaust system in fluidcommunication with the processing chamber and a vacuum source, thechamber exhaust system comprising a chamber exhaust throttle valvedownstream of the processing chamber and upstream of the vacuum source.12. The exhaust system of claim 1, further comprising: a third exhaustsystem in fluid communication with a third processing region of theprocessing chamber, the third exhaust system comprising a third throttlevalve and a third pressure gauge; and a fourth exhaust system in fluidcommunication with a fourth processing region of the processing chamber,the fourth exhaust system comprising a fourth throttle valve and afourth pressure gauge, wherein the controller is also in communicationwith the third exhaust system and the fourth exhaust system to controlthe third throttle valve or the fourth throttle valve in response tosignals from the third pressure gauge or the fourth pressure gauge. 13.The exhaust system of claim 12, wherein at least one of the firstpressure gauge, the second pressure gauge, the third pressure gauge orthe fourth pressure gauge is upstream of a respective throttle valve.14. The exhaust system of claim 12, wherein each of the first pressuregauge, the second pressure gauge, the third pressure gauge and thefourth pressure gauge are upstream of each respective throttle valve.15. The exhaust system of claim 12, wherein at least one of the firstpressure gauge, the second pressure gauge, the third pressure gauge orthe fourth pressure gauge is downstream of a respective throttle valve.16. The exhaust system of claim 12, wherein each of the first pressuregauge, the second pressure gauge, the third pressure gauge and thefourth pressure gauge are downstream of each respective throttle valve.17. The exhaust system of claim 12, wherein each of first pressuregauge, the second pressure gauge, the third pressure gauge and thefourth pressure gauge are absolute gauges.
 18. The exhaust system ofclaim 12, wherein the first pressure gauge is an absolute gauge, thesecond pressure gauge is a differential pressure gauge measuring apressure differential relative to the first pressure gauge, the thirdpressure gauge is an absolute gauge, and the fourth pressure gauge is adifferential pressure gauge measuring a pressure differential relativeto the third pressure gauge.
 19. The exhaust system of claim 12, whereinthe third pressure gauge and the fourth pressure gauge are adifferential pressure gauges measuring a pressure differential relativeto the first pressure gauge.
 20. The exhaust system of claim 12, whereinthe controller is further configured to maintain separation of gases inthe third processing region and the fourth processing region.